277 research outputs found
Spin-2 spectrum of defect theories
We study spin-2 excitations in the background of the recently-discovered
type-IIB solutions of D'Hoker et al. These are holographically-dual to defect
conformal field theories, and they are also of interest in the context of the
Karch-Randall proposal for a string-theory embedding of localized gravity. We
first generalize an argument by Csaki et al to show that for any solution with
four-dimensional anti-de Sitter, Poincare or de Sitter invariance the spin-2
excitations obey the massless scalar wave equation in ten dimensions. For the
interface solutions at hand this reduces to a Laplace-Beltrami equation on a
Riemann surface with disk topology, and in the simplest case of the
supersymmetric Janus solution it further reduces to an ordinary differential
equation known as Heun's equation. We solve this equation numerically, and
exhibit the spectrum as a function of the dilaton-jump parameter .
In the limit of large a nearly-flat linear-dilaton dimension grows
large, and the Janus geometry becomes effectively five-dimensional. We also
discuss the difficulties of localizing four-dimensional gravity in the more
general backgrounds with NS5-brane or D5-brane charge, which will be analyzed
in detail in a companion paper.Comment: 41 pages, 6 figure
Linear confinement without dilaton in bottom-up holography for walking technicolour
In PRD78(2008)055005 [arXiv:0805.1503 [hep-ph]] and PRD79(2009)075004
[arXiv:0809.1324 [hep-ph]], we constructed a holographic description of walking
technicolour theories using both a hard- and a soft-wall model. Here, we show
that the dilaton field becomes phenomenologically irrelevant for the spectrum
of spin-one resonances once a term is included in the Lagrangian that mixes the
Goldstone bosons and the longitudinal components of the axial vector mesons. We
show how this mixing affects our previous results and we make predictions about
how this description of technicolour can be tested.Comment: 7 pages, no figure
Cocaine-induced renal infarction: report of a case and review of the literature
BACKGROUND: Cocaine abuse has been known to have detrimental effects on the cardiovascular system. Its toxicity has been associated with myocardial ischemia, cerebrovascular accidents and mesenteric ischemia. The pathophysiology of cocaine-related renal injury is multifactorial and involves renal hemodynamic changes, alterations in glomerular matrix synthesis, degradation and oxidative stress, and possibly induction of renal atherogenesis. Renal infarction as a result of cocaine exposure, however, is rarely reported in the literature. CASE PRESENTATION: A 48 year-old male presented with a four-day history of severe right flank pain following cocaine use. On presentation, he was tachycardic, febrile and had severe right costovertebral angle tenderness. He had significant proteinuria, leukocytosis and elevated serum creatinine and lactate dehydrogenase. Radiographic imaging studies as well as other screening tests for thromboembolic events, hypercoagulability states, collagen vascular diseases and lipid disorders were suggestive of Cocaine-Induced Renal Infarction (CIRI) by exclusion. CONCLUSION: In a patient with a history of cocaine abuse presenting with fevers and flank pain suggestive of urinary tract infection or nephrolithiasis, cocaine-induced renal infarction must be considered in the differential diagnosis. In this article, we discuss the prior reported cases of CIRI and thoroughly review the literature available on this disorder. This is important for several reasons. First, it will allow us to discuss and elaborate on the mechanism of renal injury caused by cocaine. In addition, this review will demonstrate the importance of considering the diagnosis of CIRI in a patient with documented cocaine use and an atypical presentation of acute renal injury. Finally, we will emphasize the need for a consensus on optimal treatment of this disease, for which therapy is not yet standardized
On Supersymmetric D7-branes in the Warped Deformed Conifold
We study the supersymmetric properties of D7-branes in the warped deformed
conifold. We consider the -symmetry conditions on D7-branes in this
specific warped background, taking into account the background NS-NS 2-form
flux. While any holomorphic embedding defines a supersymmetric D7-brane in the
absence of background H-flux, most of the D7-brane embeddings considered in the
literature do not preserve supersymmetry for the warped deformed conifold
without also including brane worldvolume flux. For the simplest such embedding,
we construct numerically the worldvolume fluxnecessary to restore
supersymmetry. We also comment on the dual field theory descriptions in terms
of cascading N=1 supersymmetric gauge theories with flavors. Finally, we
discuss some possible applications of our results to moduli stabilization and
vacuum energy uplifting, gauge/gravity duality, and string inflationary model
building.Comment: 37 pages, 2 figures, v3:many clarifications and improvements to susy
restoring flu
Awareness of genetic risk in the Dominantly Inherited Alzheimer Network (DIAN)
Introduction: Although some members of families with autosomal dominant Alzheimer's disease mutations learn their mutation status, most do not. How knowledge of mutation status affects clinical disease progression is unknown. This study quantifies the influence of mutation awareness on clinical symptoms, cognition, and biomarkers. /
Methods: Mutation carriers and nonâcarriers from the Dominantly Inherited Alzheimer Network (DIAN) were stratified based on knowledge of mutation status. Rates of change on standard clinical, cognitive, and neuroimaging outcomes were examined. /
Results: Mutation knowledge had no associations with cognitive decline, clinical progression, amyloid deposition, hippocampal volume, or depression in either carriers or nonâcarriers. Carriers who learned their status midâstudy had slightly higher levels of depression and lower cognitive scores. /
Discussion: Knowledge of mutation status does not affect rates of change on any measured outcome. Learning of status midâstudy may confer shortâterm changes in cognitive functioning, or changes in cognition may influence the determination of mutation status
Fatal alcohol intoxication in women: A forensic autopsy study from Slovakia
<p>Abstract</p> <p>Background</p> <p>Plenty of information related to alcoholism can be found in the literature, however, the studies have mostly dealt with the predominance of male alcoholism and data related to addiction in women are desperately scarce and difficult to find. Basic demographic data focusing on the impact of acute alcohol intoxication on the circumstances of death and social behaviour in the alcohol addicted female population are needed especially in the prevention of alcohol related mortality.</p> <p>Methods</p> <p>A retrospective forensic autopsy study of all accidental deaths due to alcohol intoxication over a 12-year period was performed in order to evaluate the locations, circumstances, mechanisms and causes of death.</p> <p>Results</p> <p>A sample of 171 cases of intoxicated women who died due to blood alcohol concentration (BAC) equal to or higher than 2 g/kg was selected. Among them 36.26% (62/171) of women died due to acute alcohol intoxication (AAI). We noted an increase in the number of deaths in women due to AAI from 2 in 1994 up to 5 in 2005 (an elevation of 150% between the years 1994-2005). The age structure of deaths in women due to BAC and AAI followed the Gaussian distribution with a dominant group of women aged 41-50 years (45.16% and 35.09% respectively). The most frequent place of death (98%) among women intoxicated by alcohol was their own home. The study suggests a close connection between AAI and violence against women.</p> <p>Conclusions</p> <p>The increasing number of cases of death of women suffering from AAI has drawn attention to the serious problem of alcoholism in women in the Slovak Republic during the process of integration into "western" lifestyle and culture.</p
Variant-dependent heterogeneity in amyloid β burden in autosomal dominant Alzheimer's disease: cross-sectional and longitudinal analyses of an observational study
Background: Insights gained from studying individuals with autosomal dominant Alzheimer's disease have broadly influenced mechanistic hypotheses, biomarker development, and clinical trials in both sporadic and dominantly inherited Alzheimer's disease. Although pathogenic variants causing autosomal dominant Alzheimer's disease are highly penetrant, there is substantial heterogeneity in levels of amyloid β (Aβ) between individuals. We aimed to examine whether this heterogeneity is related to disease progression and to investigate the association with mutation location within PSEN1, PSEN2, or APP. Methods: We did cross-sectional and longitudinal analyses of data from the Dominantly Inherited Alzheimer's Network (DIAN) observational study, which enrols individuals from families affected by autosomal dominant Alzheimer's disease. 340 participants in the DIAN study who were aged 18 years or older, had a history of autosomal dominant Alzheimer's disease in their family, and who were enrolled between September, 2008, and June, 2019, were included in our analysis. 206 participants were carriers of pathogenic mutations in PSEN1, PSEN2, or APP, and 134 were non-carriers. 62 unique pathogenic variants were identified in the cohort and were grouped in two ways. First, we sorted variants in PSEN1, PSEN2, or APP by the affected protein domain. Second, we divided PSEN1 variants according to position before or after codon 200. We examined variant-dependent variability in Aβ biomarkers, specifically Pittsburgh-Compound-B PET (PiB-PET) signal, levels of CSF Aβ1-42 (Aβ42), and levels of Aβ1-40 (Aβ40). Findings: Cortical and striatal PiB-PET signal showed striking variant-dependent variability using both grouping approaches (p0¡7), and CSF Aβ42 levels (codon-based grouping: p=0¡49; domain-based grouping: p=0¡095). Longitudinal PiB-PET signal also varied across codon-based groups, mirroring cross-sectional analyses. Interpretation: Autosomal dominant Alzheimer's disease pathogenic variants showed highly differential temporal and regional patterns of PiB-PET signal, despite similar functional progression. These findings suggest that although increased PiB-PET signal is generally seen in autosomal dominant Alzheimer's disease, higher levels of PiB-PET signal at an individual level might not reflect more severe or more advanced disease. Our results have high relevance for ongoing clinical trials in autosomal dominant Alzheimer's disease, including those using Aβ PET as a surrogate marker of disease progression. Additionally, and pertinent to both sporadic and autosomal dominant Alzheimer's disease, our results suggest that CSF and PET measures of Aβ levels are not interchangeable and might reflect different Aβ-driven pathobiological processes. Funding: National Institute on Aging, Doris Duke Charitable Foundation, German Center for Neurodegenerative Diseases, Japanese Agency for Medical Research and Development
Brane-World Gravity
The observable universe could be a 1+3-surface (the "brane") embedded in a
1+3+\textit{d}-dimensional spacetime (the "bulk"), with Standard Model
particles and fields trapped on the brane while gravity is free to access the
bulk. At least one of the \textit{d} extra spatial dimensions could be very
large relative to the Planck scale, which lowers the fundamental gravity scale,
possibly even down to the electroweak ( TeV) level. This revolutionary
picture arises in the framework of recent developments in M theory. The
1+10-dimensional M theory encompasses the known 1+9-dimensional superstring
theories, and is widely considered to be a promising potential route to quantum
gravity. At low energies, gravity is localized at the brane and general
relativity is recovered, but at high energies gravity "leaks" into the bulk,
behaving in a truly higher-dimensional way. This introduces significant changes
to gravitational dynamics and perturbations, with interesting and potentially
testable implications for high-energy astrophysics, black holes, and cosmology.
Brane-world models offer a phenomenological way to test some of the novel
predictions and corrections to general relativity that are implied by M theory.
This review analyzes the geometry, dynamics and perturbations of simple
brane-world models for cosmology and astrophysics, mainly focusing on warped
5-dimensional brane-worlds based on the Randall--Sundrum models. We also cover
the simplest brane-world models in which 4-dimensional gravity on the brane is
modified at \emph{low} energies -- the 5-dimensional Dvali--Gabadadze--Porrati
models. Then we discuss co-dimension two branes in 6-dimensional models.Comment: A major update of Living Reviews in Relativity 7:7 (2004)
"Brane-World Gravity", 119 pages, 28 figures, the update contains new
material on RS perturbations, including full numerical solutions of
gravitational waves and scalar perturbations, on DGP models, and also on 6D
models. A published version in Living Reviews in Relativit
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